JP7165499B2 - Charged particle beam therapy system - Google Patents

Description

The present invention relates to a charged particle beam therapy system.

2. Description of the Related Art Conventionally, an apparatus described in Patent Document 1, for example, is known as a charged particle beam therapy apparatus that treats an affected area of a patient by irradiating it with a charged particle beam. In the charged particle beam therapy system described in Patent Literature 1, a charged particle beam accelerated by an accelerator is made incident on an attenuation unit (degrader) to attenuate the energy, and then irradiated to an object to be irradiated.

JP 2015-181655 A

In the charged particle beam therapy system as disclosed in Patent Document 1, when the charged particle beam passes through the attenuation part, the charged particles are scattered by the attenuation part and the beam size of the charged particle beam increases. Therefore, when highly accurate irradiation is required, it is necessary to adjust the beam size of the charged particle beam by cutting part of the charged particle beam using a collimator or the like. However, cutting a portion of the charged particle beam in this way lowers the efficiency of using the particles, which causes a problem of a decrease in the beam current of the charged particle beam. Therefore, it is required to suppress the expansion of the beam size of the charged particle beam.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a charged particle beam therapy system capable of suppressing an increase in beam size while suppressing a decrease in beam current of a charged particle beam. With the goal.

A charged particle beam therapy system according to one aspect of the present invention includes an accelerator that accelerates charged particles and emits a charged particle beam, and by making the charged particle beam emitted from the accelerator incident, the energy of the charged particle beam is Attenuation unit for lowering, magnetic field generation unit for generating a magnetic field having a component in the same direction as the emitted direction of the charged particle beam in the attenuation unit, and irradiation unit for irradiating the irradiated object with the charged particle beam that has passed through the magnetic field generation unit. And prepare.

This charged particle beam therapy system includes, in the attenuation section, a magnetic field generation section that generates a magnetic field having a component in the same direction as the emission direction of the charged particle beam. By generating a magnetic field in the attenuation section in the same direction as the emission direction of the charged particle beam in this way, a force acts on the charged particles scattered by the attenuation section in the direction of rotation about the emission direction of the charged particle beam. do. As a result, the scattered charged particles move in the emission direction in a trajectory that wraps around the axis of the charged particle beam. Therefore, the scattered charged particles are suppressed from diverging in the direction away from the axis of the charged particle beam, and the expansion of the beam size is suppressed. Therefore, it is possible to suppress the expansion of the beam size while suppressing the decrease in the beam current of the charged particle beam.

In one form, the magnetic field generator may generate a magnetic field using a superconducting electromagnet. With this configuration, a strong magnetic field of about 10 T, for example, can be generated, so that the beam size expansion of the charged particle beam can be effectively suppressed.

In one form, the magnetic field generator may have a first generator arranged upstream of the attenuation section and a second generator arranged downstream of the attenuation section. According to this configuration, it becomes easier to generate a uniform magnetic field in the emission direction in the attenuation section. Therefore, it is possible to effectively suppress the expansion of the beam size of the charged particle beam.

ADVANTAGE OF THE INVENTION According to this invention, the charged particle beam therapy apparatus which can suppress the expansion of a beam size is provided, suppressing the decline of the beam current of a charged particle beam.

1 is a schematic configuration diagram of a charged particle beam therapy system according to one embodiment; FIG. 2 is a schematic configuration diagram of the vicinity of an irradiation unit of the charged particle beam therapy system of FIG. 1; FIG. FIG. 10 is a diagram showing manipulations set for a tumor; It is a perspective sectional view showing roughly the composition of an energy adjustment part. FIG. 3 is a schematic configuration diagram showing the configuration of an energy adjustment unit; 5 is a diagram for explaining the effect of the magnetic field generator of FIG. 4; FIG. (a) is a simulation result showing scattering of charged particle beams when the magnetic field generator is not used, and (b) is a simulation result showing scattering of charged particle beams when the magnetic field generator is used. (a) is a diagram showing the distribution of charged particles when the magnetic field generator is not used, and (b) is a diagram showing the distribution of the charged particles when the magnetic field generator is used.

A charged particle beam therapy system according to an embodiment of the present invention will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and overlapping descriptions are omitted.

As shown in FIG. 1, a charged particle beam therapy apparatus 1 according to one embodiment of the present invention is an apparatus used for cancer treatment by radiotherapy, and charged particles generated by an ion source (not shown) Accelerator 3 that accelerates and emits a charged particle beam, an irradiation unit 2 that irradiates the object to be irradiated with the charged particle beam, and a beam transport line 41 that transports the charged particle beam emitted from the accelerator 3 to the irradiation unit 2 , and an energy adjustment unit 20 provided between the accelerator 3 and the irradiation unit 2 on the beam transport line 41 . The irradiation unit 2 is attached to a rotating gantry 5 that surrounds the treatment table 4 . The irradiation unit 2 is configured to be rotatable around the treatment table 4 by a rotating gantry 5 .

FIG. 2 is a schematic configuration diagram of the vicinity of the irradiation unit of the charged particle beam therapy system of FIG. In the following description, the terms "X direction", "Y direction", and "Z direction" are used. The “Z direction” is the direction in which the base axis AX of the charged particle beam B extends, and is the depth direction of the charged particle beam B irradiation. The "base axis AX" is the irradiation axis of the charged particle beam B when it is not deflected by the scanning electromagnet 6, which will be described later. FIG. 2 shows how the charged particle beam B is irradiated along the base axis AX. "X direction" is one direction in a plane perpendicular to the Z direction. “Y direction” is a direction orthogonal to the X direction in a plane orthogonal to the Z direction.

First, referring to FIG. 2, a schematic configuration of a charged particle beam therapy system 1 according to this embodiment will be described. In the following description, a case where the charged particle beam therapy apparatus 1 is an irradiation apparatus according to the scanning method will be described. The scanning method is not particularly limited, and line scanning, raster scanning, spot scanning, or the like may be employed. Furthermore, the irradiation method of the charged particle beam therapy apparatus 1 is not limited to the scanning method, and any irradiation method such as the wobbler method, broad beam method, conformal irradiation method, etc. may be employed. As shown in FIG. 2 , the charged particle beam therapy system 1 includes an accelerator 3 , an irradiation section 2 , a beam transport line 41 and a control section 7 .

The accelerator 3 is a device that accelerates charged particles and emits a charged particle beam B having a preset energy. Examples of the accelerator 3 include a cyclotron, a synchrotron, a synchrocyclotron, a linac, and the like. This accelerator 3 is connected to a control unit 7 and the supplied current is controlled. A charged particle beam B generated by the accelerator 3 is transported to the irradiation nozzle 9 by a beam transport line 41 . The beam transport line 41 connects the accelerator 3, the energy adjustment unit 20, and the irradiation unit 2, and transports the charged particle beam emitted from the accelerator 3 and energy-adjusted by the energy adjustment unit 20 to the irradiation unit 2. do.

The charged particle beam therapy system 1 further includes a beam chopper 16 that is arranged inside the accelerator 3 and blocks charged particles emitted from the ion source. When the beam chopper 16 is in the operating state (ON), the charged particles emitted from the ion source are blocked and the charged particle beam B is not emitted from the accelerator 3 . When the beam chopper 16 is in a stopped state (OFF), the charged particle beam B is emitted from the accelerator 3 without blocking the charged particles emitted from the ion source. A beam chopper switch (not shown) switches between an operating state and a stopped state of the beam chopper 16 . Note that means other than the beam chopper may be used as means for switching between irradiation and non-irradiation of the charged particle beam. For example, a shutter may be provided in the beam transport line 41 to block the charged particle beam B with the shutter. Alternatively, a deflector (electromagnet) provided in the accelerator 3 may be used to emit the charged particle beam B from the accelerator 3 only when irradiating.

The irradiation unit 2 irradiates a charged particle beam B to a tumor (object to be irradiated) 14 in the body of a patient 15 . The charged particle beam B is obtained by accelerating charged particles at high speed, and includes, for example, a proton beam, a heavy particle (heavy ion) beam, an electron beam, and the like. Specifically, the irradiation unit 2 is a device that irradiates the tumor 14 with a charged particle beam B emitted from an accelerator 3 that accelerates charged particles generated by an ion source (not shown) and transported through a beam transport line 41. . The irradiation unit 2 includes a scanning electromagnet (scanning unit) 6 , a quadrupole electromagnet 8 , a profile monitor 11 , a dose monitor 12 , flatness monitors 13 a and 13 b and a degrader 30 . Scanning electromagnet 6 , monitors 11 , 12 , 13 a and 13 b , quadrupole electromagnet 8 , and degrader 30 are housed within irradiation nozzle 9 .

The scanning electromagnet 6 includes an X-direction scanning electromagnet 6a and a Y-direction scanning electromagnet 6b. Each of the X-direction scanning electromagnet 6a and the Y-direction scanning electromagnet 6b is composed of a pair of electromagnets. The magnetic field between the pair of electromagnets is changed according to the current supplied from the control unit 7, and charged particles passing between the electromagnets are detected. Scan line B. The X-direction scanning electromagnet 6a scans the charged particle beam B in the X direction, and the Y-direction scanning electromagnet 6b scans the charged particle beam B in the Y direction. These scanning electromagnets 6 are arranged in this order on the base axis AX and downstream of the accelerator 3 in the direction in which the charged particle beam B is emitted.

The quadrupole electromagnet 8 includes an X-direction quadrupole electromagnet 8a and a Y-direction quadrupole electromagnet 8b. The X-direction quadrupole electromagnet 8 a and the Y-direction quadrupole electromagnet 8 b narrow and converge the charged particle beam B according to the current supplied from the control unit 7 . The X-direction quadrupole electromagnet 8a converges the charged particle beam B in the X direction, and the Y-direction quadrupole electromagnet 8b converges the charged particle beam B in the Y direction. The beam size of the charged particle beam B can be changed by changing the amount of aperture (convergence amount) by changing the current supplied to the quadrupole electromagnet 8 . The quadrupole electromagnets 8 are arranged on the base axis AX between the accelerator 3 and the scanning electromagnets 6 in this order. The beam size is the size of the charged particle beam B on the XY plane. Also, the beam shape is the shape of the charged particle beam B on the XY plane.

The profile monitor 11 detects the beam shape and position of the charged particle beam B for alignment during initialization. The profile monitor 11 is arranged between the quadrupole electromagnet 8 and the scanning electromagnet 6 on the base axis AX. The dose monitor 12 detects the intensity of the charged particle beam B. FIG. The dose monitor 12 is arranged downstream of the scanning electromagnet 6 on the base axis AX. The flatness monitors 13a and 13b detect and monitor the beam shape and position of the charged particle beam B. FIG. The flatness monitors 13 a and 13 b are arranged on the base axis AX and downstream of the charged particle beam B from the dose monitor 12 . Each monitor 11, 12, 13a, 13b outputs the detected detection result to the control unit 7. FIG.

The degrader 30 finely adjusts the energy of the charged particle beam B by reducing the energy of the charged particle beam B passing therethrough. In this embodiment, the degrader 30 is provided at the tip 9 a of the irradiation nozzle 9 . The tip 9a of the irradiation nozzle 9 is the end of the charged particle beam B on the downstream side. The degrader 30 inside the irradiation nozzle 9 can also be omitted.

The control unit 7 is composed of, for example, a CPU, a ROM, a RAM, and the like. The controller 7 controls the accelerator 3, the scanning electromagnet 6 and the quadrupole electromagnet 8 based on the detection results output from the monitors 11, 12, 13a and 13b. Further, in this embodiment, the control unit 7 feeds back the detection results of the monitors 11, 12, 13a, and 13b, and controls the quadrupole electromagnet 8 so that the beam size of the charged particle beam B is constant. .

The controller 7 of the charged particle beam therapy system 1 is also connected to a treatment planning system 100 that plans treatment for charged particle beam therapy. The treatment planning apparatus 100 measures the tumor 14 of the patient 15 by CT or the like before treatment, and plans the dose distribution (the dose distribution of the charged particle beam to be irradiated) at each position of the tumor 14 . Specifically, treatment planning system 100 creates a treatment planning map for tumor 14 . The treatment planning apparatus 100 transmits the created treatment planning map to the controller 7 .

When performing charged particle beam irradiation by scanning, the tumor 14 is virtually divided into a plurality of layers in the Z direction, and one layer is scanned and irradiated with the charged particle beam. Then, after the charged particle beam irradiation on the one layer is completed, the next adjacent layer is irradiated with the charged particle beam.

When the charged particle beam B is irradiated by the scanning method using the charged particle beam therapy system 1 shown in FIG. 2, the quadrupole electromagnet 8 is activated (ON) so that the passing charged particle beam B converges.

Subsequently, the charged particle beam B is emitted from the accelerator 3 . In addition, the range of the charged particle beam B is adjusted by adjusting the charged particle beam B emitted from the accelerator 3 by the energy adjustment unit 20 . The emitted charged particle beam B is scanned by the control of the scanning electromagnet 6 . As a result, the charged particle beam B is irradiated onto the tumor 14 while scanning within the irradiation range of one layer set in the Z direction. After the irradiation of one layer is completed, the charged particle beam B is irradiated to the next layer.

A charged particle beam irradiation image of the scanning electromagnet 6 according to the control of the controller 7 will be described with reference to FIGS. 3(a) and 3(b). FIG. 3(a) shows an irradiated object virtually sliced into multiple layers in the depth direction, and FIG. 3(b) shows a scanning image of a charged particle beam in one layer viewed from the depth direction. , respectively.

As shown in FIG. 3A, the object to be irradiated is virtually sliced into a plurality of layers in the irradiation depth direction. Layer L ₁ , layer L ₂ , . . . layer L n _{− 1} , layer L _n , layer L _{n +1} , . Also, as shown in FIG. 3B, the charged particle beam B is irradiated onto a plurality of irradiation spots on the layer _Ln while drawing a beam trajectory TL. That is, the irradiation nozzle 9 controlled by the controller 7 moves on the beam trajectory TL.

Next, the configuration of the energy adjustment unit 20 included in the charged particle beam therapy system 1 according to this embodiment will be described with reference to FIGS. 4 and 5. FIG. The energy adjustment unit 20 has an attenuation unit 21 that reduces the energy of the charged particle beam B and a magnetic field generation unit 22 that generates a magnetic field in the attenuation unit 21 .

The attenuation unit 21 is a member that lowers the energy of the charged particle beam B emitted from the accelerator 3 by allowing the charged particle beam B to enter. The damping portion 21 has a first damping material 21A and a second damping material 21B. Each of the first damping member 21A and the second damping member 21B has a plurality of protrusions 23 in the shape of a right-angled triangular prism. Each projecting portion 23 has a first surface 23a perpendicular to the charged particle beam B and a second surface 23b inclined with respect to the charged particle beam B. As shown in FIG. The first damping member 21A and the second damping member 21B have substantially the same shape, and are arranged so that the protruding portion 23 of the first damping member 21A and the protruding portion 23 of the second damping member 21B face each other. . The second surface 23b of the projecting portion 23 of the first damping member 21A and the second surface 23b of the projecting portion 23 of the second damping member 21B are parallel to each other and spaced apart. The charged particle beam B enters the attenuation section 21 from the first surface 23a of the protrusion 23 of the first attenuation material 21A and exits the attenuation section 21 from the first surface 23a of the protrusion 23 of the second attenuation material 21B. emit.

The first damping material 21A and the second damping material 21B are each connected to a drive source (not shown) and configured to be displaceable in a direction perpendicular to the charged particle beam B. As shown in FIG. As a result, the thickness of the portion through which the charged particle beam B passes (the sum of the thickness of the first damping material 21A and the thickness of the second damping material 21B on the irradiation axis of the charged particle beam B) is adjusted, Attenuation of the energy of the charged particle beam B by 21 can be adjusted.

Examples of materials that constitute the damping section 21 (the first damping material 21A and the second damping material 21B) include substances with a small atomic number, such as beryllium (Be) and carbon (C). In the present embodiment, beryllium (Be) is preferably used from the viewpoint of suppressing scattering of the charged particle beam B by the attenuation section 21 . The materials forming the first damping material 21A and the second damping material 21B may be the same or different. Further, the shapes of the first damping member 21A and the second damping member 21B are not particularly limited, and can be changed as appropriate.

The magnetic field generating section 22 is a section that causes the attenuation section 21 to generate a magnetic field, and has a first generating section 22A and a second generating section 22B. The first generator 22A is arranged upstream of the attenuation section 21 (the accelerator 3 side), and the second generator 22B is arranged downstream of the attenuation section 21 (the irradiation section 2 side). Each of the first generator 22A and the second generator 22B has a superconducting electromagnet 24 and a cryostat 25 that accommodates the superconducting electromagnet 24 . In the present embodiment, the first generating section 22A and the second generating section 22B are provided adjacent to the damping section 21, and are provided between the damping section 21 and the first generating section 22A and between the damping section 21 and the second generating section 21. No other parts are arranged between the part 22B.

The superconducting electromagnet 24 is an electromagnet in which a superconducting wire is wound in an annular shape, and generates a magnetic field by applying an electric current to the superconducting wire in a state of being cooled to a superconducting state. A current in the same direction is applied to the superconducting electromagnet 24 of the first generating portion 22A and the superconducting electromagnet 24 of the second generating portion 22B. Thereby, a magnetic field H is formed in the attenuation portion 21 located between the first generation portion 22A and the second generation portion 22B. More specifically, the superconducting electromagnet 24 is arranged such that its central axis substantially coincides with the charged particle beam B axis. By arranging the superconducting electromagnets 24 in this manner, a magnetic field H having a component in the same direction as the emission direction of the charged particle beam B is formed in the portion through which the charged particle beam B passes in the attenuation section 21 . In addition, in the direction along the axis of the charged particle beam B, the range in which the magnetic field H is generated in the same direction as the emission direction is from one end on the upstream side of the attenuation section 21 to the other end on the downstream side of the attenuation section 21. It preferably contains a region. Note that the range in which the magnetic field H is generated in the direction along the axis of the charged particle beam B may include only a part of the attenuation section 21 . Also, the range in which the magnetic field H is generated may be set wider than the width of the attenuation section 21 . The strength of the magnetic field H can be, for example, about 0.5T to 10T.

In addition, the width of the range in which the magnetic field H in the same direction as the emission direction of the magnetic field H is formed in the direction perpendicular to the emission direction of the charged particle beam B is at least the attenuation part It can be made larger than the beam size d of the charged particle beam B before entering 21 . The width of the range in which the magnetic field H is formed in the same direction as the emission direction, in the direction perpendicular to the emission direction, is the beam size d of the charged particle beam B when emitted from the attenuation unit 21 (that is, the charged particle diverges possible range), and may include the entire damping section 21 .

The cryostat 25 is an annular container. Superconducting electromagnet 24 is cooled within cryostat 25 . The cryostat 25 is provided with an opening 25a in its central portion. The center of the opening 25 a is substantially aligned with the axis of the charged particle beam B, and the charged particle beam B passes through the opening 25 a of the cryostat 25 and enters (or exits) the attenuation section 21 . The shape of the cryostat 25 is not particularly limited and can be changed as appropriate.

Next, referring to FIG. 6, the effect of the magnetic field generator 22 will be described. FIG. 6 is a diagram for explaining the effect of the magnetic field generator 22. FIG. As shown in FIG. 6, by generating a magnetic field H in the same direction as the emitted direction of the charged particle beam B, the charged particles P scattered by the attenuation section 21 (see FIGS. 4 and 5) are A force acts in the rotation direction R about the emission direction of the line B as an axis. As a result, the charged particle P moves in the emission direction while rotating around the axis of the charged particle beam B. FIG. That is, under the influence of the magnetic field H, the charged particle P moves while drawing a spiral trajectory that wraps around the axis of the charged particle beam B. As shown in FIG. As a result, the scattered charged particles P are suppressed from diverging in the direction away from the axis of the charged particle beam B, so that the beam size of the charged particle beam B can be suppressed from expanding.

Next, simulation results regarding scattering of the charged particle beam B will be described with reference to FIGS. 7 and 8. FIG. FIG. 7(a) is a simulation result showing the scattering of the charged particle beam B when the magnetic field generator 22 is not used, and FIG. 7(b) is the scattering of the charged particle beam B when the magnetic field generator 22 is used. It is a simulation result showing. 8A shows the distribution of charged particles when the magnetic field generator 22 is not used, and FIG. 8B shows the distribution of charged particles when the magnetic field generator 22 is used. be.

In the simulation of the scattering of the charged particle beam B, parameters such as the current value of the charged particle beam B, the material of the attenuation part, and the measurement position of the beam size d of the charged particle beam B are set to constant conditions, and the magnetic field H is used. The beam size d when the magnetic field H is used and the beam size d when the magnetic field H is not used are compared.

As shown in FIG. 7A, when the magnetic field generator 22 is not used, the beam size d of the charged particle beam B gradually expands from within the attenuation unit 21 . On the other hand, as shown in FIG. 7B, when the magnetic field generator 22 is used, the expansion of the beam size d is suppressed within the range where the attenuation unit 21 and the magnetic field H are formed. . The beam size d of the charged particle beam B gradually expands after passing through the magnetic field H range. The beam size d of the charged particle beam B at the measurement position is smaller than the beam size d when the magnetic field generator 22 is not used. From this result, it can be confirmed that the magnetic field H generated by the magnetic field generator 22 suppresses the divergence of the charged particles in the attenuation unit 21 and suppresses the expansion of the beam size d of the charged particle beam B. FIG.

8 shows the distribution of charged particles at the measurement position of the beam size d of the charged particle beam B in phase space based on the simulation results shown in FIG. 8(a) and 8(b), the X axis indicates the spatial coordinates of a certain direction in a plane perpendicular to the axis of the charged particle beam B, and the X′ axis indicates the X direction with respect to the emission direction of the charged particle beam B. Changes in coordinates (ie particle angles) are shown. 8A and 8B, the width in the X-axis direction corresponds to the beam size d of the charged particle beam B. In FIG. 8A and 8B, the width in the X-axis direction in FIG. 8B (when the magnetic field generator 22 is used) is is smaller than the width in the X-axis direction in the non-used case). 8(a) and 8(b), the magnetic field H generated by the magnetic field generator 22 suppresses the divergence of the charged particles in the attenuation unit 21 and suppresses the expansion of the beam size d of the charged particle beam B. It can be confirmed that The width in the X'-axis direction in FIG. 8A is substantially the same as the width in the X'-axis direction in FIG. 8B. Therefore, although the attenuation unit 21 scatters the charged particles to the same extent (that is, the shape of the attenuation unit 21 and the material forming the attenuation unit 21 are the same), the magnetic field H causes the charged particle beam B to be scattered. It can be confirmed that the magnetic field H suppresses the divergence in the direction away from the axis.

As described above, the charged particle beam therapy system 1 includes the magnetic field generation section 22 that generates the magnetic field H in the same direction as the emission direction of the charged particle beam B in the attenuation section 21 . By causing the attenuation unit 21 to generate the magnetic field H in the same direction as the emission direction of the charged particle beam B in this way, the charged particles P scattered by the attenuation unit 21 have a magnetic field with the emission direction of the charged particle beam B as an axis. A force acts in the direction of rotation R (see FIG. 6). As a result, the scattered charged particles P move in the emission direction along a trajectory that wraps around the axis of the charged particle beam B. FIG. Therefore, the scattered charged particles P are suppressed from diverging in the direction away from the axis of the charged particle beam B, and the expansion of the beam size d is suppressed. Therefore, it is possible to reduce the portion cut by the collimator or the like (that is, it is possible to improve the particle utilization rate). is possible.

Also, the magnetic field generator 22 generates a magnetic field H using a superconducting electromagnet 24 . As a result, a strong magnetic field H of, for example, about 10 T can be generated, so that expansion of the beam size d of the charged particle beam B can be effectively suppressed.

Further, the magnetic field generator 22 has a first generator 22A arranged upstream of the attenuation section 21 and a second generator 22B arranged downstream of the attenuation section 21 . This makes it easier to generate a uniform magnetic field H in the emission direction in the attenuation section 21 . Therefore, the expansion of the beam size d of the charged particle beam B can be effectively suppressed.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be adopted. For example, in the above embodiment, the magnetic field generator 22 generates the magnetic field by the superconducting electromagnet 24, but the magnetic field generator 22 may generate the magnetic field H by means other than the superconducting electromagnet 24. For example, a permanent magnet and/or a normal conducting electromagnet may be used instead of the superconducting electromagnet 24 .

Also, the configuration of the irradiation unit 2 is not limited to that shown in FIG. 2, and can be changed as appropriate.

Further, in the above embodiment, an example in which the energy adjustment unit 20 is arranged immediately below the accelerator 3 (immediately downstream with respect to the emission direction of the charged particle beam B) has been described, but the energy adjustment unit 20 is arranged There is no particular limitation on the position where the From the viewpoint of improving the particle utilization efficiency, it is preferable to arrange the energy adjustment unit 20 directly below the accelerator 3 and suppress the expansion of the beam size d by the magnetic field generation unit 22 .

In the above embodiment, the magnetic field generator 22 includes two generators, the first generator 22A and the second generator 22B. However, the magnetic field generator 22 includes only one generator. may In this case, the generating section may be arranged upstream or downstream of the damping section 21 . Furthermore, the magnetic field generator 22 may include three or more generators.

DESCRIPTION OF SYMBOLS 1... Charged particle beam therapy apparatus, 2... Irradiation part, 3... Accelerator, 14... Tumor (object to be irradiated), 20... Energy adjustment part, 21... Attenuation part, 22... Magnetic field generation part, 22A... First generation part, 22B... Second generator, 24... Superconducting electromagnet, B... Charged particle beam, H... Magnetic field.

Claims (4)

an accelerator that accelerates charged particles and emits a charged particle beam;
an attenuation unit that reduces the energy of the charged particle beam by allowing the charged particle beam emitted from the accelerator to enter;
a magnetic field generator that generates a magnetic field having a component in the same direction as the direction in which the charged particle beam is emitted in a region from one end of the attenuation section on the upstream side to the other end of the attenuation section on the downstream side;
an irradiation unit that irradiates an object to be irradiated with the charged particle beam that has passed through the magnetic field generation unit;
with
The magnetic field generator has at least one of a first generator arranged upstream of the attenuation unit and a second generator arranged downstream of the attenuation unit ,
The first generator is arranged such that the central axis of the first generator coincides with the axis of the charged particle beam, and the second generator is arranged such that the central axis of the second generator is aligned with the charged particle beam. A charged particle beam therapy system positioned so as to coincide with the axis of . The charged particle beam therapy system according to claim 1, wherein the magnetic field generator generates the magnetic field using a superconducting electromagnet. The charged particle according to claim 1 or 2, wherein the magnetic field generation section has a first generation section arranged upstream of the attenuation section and a second generation section arranged downstream of the attenuation section. Radiotherapy equipment. an accelerator that accelerates charged particles and emits a charged particle beam;
an attenuation unit that reduces the energy of the charged particle beam by allowing the charged particle beam emitted from the accelerator to enter;
a magnetic field generator that generates a magnetic field having a component in the same direction as the direction in which the charged particle beam is emitted in a region from one end of the attenuation section on the upstream side to the other end of the attenuation section on the downstream side;
an irradiation unit that irradiates an object to be irradiated with the charged particle beam that has passed through the magnetic field generation unit;
with
The magnetic field generation section has a first generation section arranged upstream of the attenuation section and a second generation section arranged downstream of the attenuation section,
The charged particle beam therapy apparatus, wherein the first generating section and the second generating section are provided adjacent to the attenuation section.

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